An OLED display is a display device in which light is emitted by means of the electroluminescence of fluorophor or phosphor organic compounds. The OLED display drives a plurality of OLEDs to display images. Each OLED includes an anode, an organic function layer and a cathode. The organic function layer generally includes an emission layer (EML), an electron transport layer (ETL) and a hole transport layer (HTL). Thus, the balance between injected electrons and injected holes can be improved, and hence the luminous efficiency can be improved.
In the OLED, in order to display the entire color gamut, for instance, red (R), green (G) and blue (B) EMLs may be respectively patterned. In order to pattern the EMLs, a shadow mask can be used in the case of small molecular OLEDs, and inkjet printing method or laser induced thermal imaging (LITI) method may be used in the case of polymer OLEDs. An organic layer may be finely patterned by the LITI method. The LITI method may be used in the case of large area. Moreover, the LITI method has the advantage of high resolution.
High pixels per inch (PPI) display devices belong to a main development trend of the current display device, and high PPI OLED display panels are of a top-emission structure. An OLED production technology mainly adopts a fine metal mask (FMM) and a side-by-side pixel arrangement to achieve the full-color display of the OLED.